Rolling mill workpiece delivery thickness control

ABSTRACT

A workpiece delivery thickness control is provided for use with a programmed digital process control computer for controlling each operating stand of a rolling mill to improve mill setup relative to at least one selected operational variable, such as stand roll force, for a workpiece of known gauge and grade. For this purpose predetermined ratio comparisons are made between the measured value of the selected variable and the predicted value of that variable, for each stand operation with a workpiece. These ratio comparisons, determined in a predetermined manner in relation to previous rolling experience for each stand relative to the same gauge and grade category of workpiece, are stored in a classified memory location to improve subsequent operation with the same category of gauge and grade workpieces. The ratio comparison after each workpiece is rolled is weighted together in a predetermined manner for each stand operation with the ratio determined from previous rolling experience with a similar workpiece to provide operation control information for improving the stand operation with a subsequent workpiece to provide a desired delivery gauge for that workpiece.

United States Patent m1 3,631,697

[72] Inventors sAntholg' D. Deramo FOREIGN PATENTS wlssv e; V Andrew w.Smith Jr. Pittsburgh; Frank 1,991,484 1 1/1967 Great Britain 72/8 E.Wallace, Irwin; Robert J. Goldbach, Pnmary ExaminerMilton S. MehrMcKggspofl, ll f P Attorneys-F. H. Henson and R. G. Brodahl [211 App].No. 852,627

'I d A 25 1969 ga 1 24 372 ABSTRACT: A workpiece delivery thicknesscontrol is pro- 73 Assignee w fl h Electric Corporation vided for usewith a programmed digital process control compm p puter for controllingeach operating stand of a rolling mill to improve mill setup relative toat least one selected operational variable, such as stand roll force,for a workpiece of known [54] ROLLING MILL WORKPIECE DELIVERY gauge andgrade. For this purpose predetermined ratio com- THICKNESS CONTROLparisons are made between the measured value of the selected 22Claims,7Drawing Figs. variable and the predicted value of that variable,for each 52 us. Cl 72/8 with wmkpiece These ratio [51] Int Cl Bub 37/00determined in a predetermined manner in relation to previous rollingexperience for each stand relative to the same gauge [50] Field ofSearch 72/6-12, and grade g y of workpiece are stored in a classifiedmemory locatlon to improve subsequent operation with the [56] ReferencesCited same casgory ofhgaug; and gradilwgrkpiecels. 'Lhe rati? comparisonter eac wor pieceis ro e IS weig te toget er ma UNITED STATES PATENTSpredetermined manner for each stand operation with the ratio 1186,206/1965 Lufibmokw 72/9 determined from previous rolling experience with asimilar workpiece to provide operation control information for improvingthe stand operation with a subsequent workpiece to provide a desireddelivery gauge for that workpiece.

'ROUGHING MILL FINISHING MILL scaswoovm EIQEY' QSX POSITION oerscroaocrscron 3O Y IO 35 1 I H STRIP CHARACTERISTICS PROCESS CORE MEMORYCONTROL COMPUTER DRUM MEMORY IAIENIED JAN 4 I972 LESS THAN THIS LASTSTAND DELIVERY LESS THAN THIS LAST STAND DELIVERY GAUGE OR HEIGHT IN MILS GAUGE OR HEIGHT IN MI LS SHEEI 2 [IF 5 WORKPIECE cmc (mm AL sumo NOPERATION CORRECTION FACTORS) FIG. 2

WORKPIECE GRADE (UPDATED STAND N OPERATION CORRECTION FACTORS) FIG. 3

ROLLING MILL WORKPIECE DELIVERY THICKNESS CONTROL BACKGROUND OF THEINVENTION The present invention relates to the improved control of arolling mill, and more particularly to the provision of a scheduled,mill stand setup based upon empirical model equation information.

In the operation of particularly a metal rolling mill having at leastone stand, the unloaded roll opening and the speed, for each mill stand,as well as other variables, are predictably set up by a process controlcomputer operative with predetermined model equations to provide adesired workpiece reduction resulting in an on gauge delivery workproduct from each stand. It may be assumed that the loaded roll openingat a stand equals the stand delivery gauge since there is substantiallyno elastic workpiece recovery. The predictive set up assumptions may bein error, and certain other mill-operating parameters effect the standloaded roll operation after setup conditions have been established, suchthat a stand gauge control system is employed to closely control thestand delivery gauge work product. Recent experience with metal-rollingmills, such as a tandem hot strip mill, has demonstrated that a rollforce gauge control system is particularly effective for this purpose.Such a roll force gauge control system employs Hookes Law in controllingthe screw down position at a given rolling stand, with the loaded rollopening being substantially the delivery workpiece height H and, undernormal rolling conditions, equal to the unloaded roll opening orscrewdown position SD plus the determined offset and the mill springstretch, which is obtained by the dividing of the measured stand rollseparating force F by the predetermined mill spring constant M. Toembody this rolling principle in a roll force gauge control system, aload cell or other stand roll force detector measures theroll-separating force F. The screwdown position is then controlled tominimize the roll force changes from a reference or setpoint value tothereby hold the loaded roll opening at a substantially constant anddesired value. Once the unloaded roll opening for each stand andadditionally the stand speed setup are determined by the process controlcomputer for a particular workpiece stand pass, the rolling operation isbegun. The respective screwdowns are then continuously controlled toregulate the workpiece delivery gauge from each mill stand.

A more detailed discussion of the theory behind a roll force workpiecegauge control operation can be found in US. Pat. No. 2,726,541 of R. B.Sims. In addition, reference is made to a background informationproviding article entitled, Automatic Gauge Control for Modern Hot StripMills, by .l. W. Wallace which appeared in the Dec. 1967 Iron and SteelEngineer at pages 75 to 86.

It is commercially desirable to provide predictive mill stand setupvalues, which in addition to providing a better on gauge rolling ofparticularly the head end of the workpiece strip, also establishesmill-operating conditions which are compatible with the subsequent takeover relative to the remainder of the workpiece strip by the attendantand more conventional automatic roll force gauge control system once allof the mill stands become full.

Previously mill operational setup parameters have been set up by a humanoperator. As the measured rolling mill variables have increased both innumber and complexity, a process control computer has been applied totake over the dominant role in determining mill stand setup, with theoperator serving as a backup. The process control computer has operatedto establish certain mill settings according to a predeterminedmathematical equation model. As each workpiece strip or coil is rolled,information is gathered from the various mill operation sensors toimprove the setup relative to the rolling of the next workpiece. Such asystem has proved satisfactory in that the original predictive setupvalues based upon the model equations can be adapted to a better millsetup by off line data manipulation determined from the rolling of theworkpieces.

In rolling mills operated under control of a digital process controlcomputer, in an effort to provide substantially on gauge delivery stripproduct from each stand during the rolling of individual workpieces, aforce feed forward control system has been provided whereby, for as longas the workpiece grade is the same, the actual roll force for each ofthe respective stands for the rolling of at least one previous workpieceis utilized to determine whether the general roll force levelestablished by the model equations should be higher or lower as comparedto at least this one previous similar alloy grade workpiece strip.

In general, a process control computer includes a memory which containsa stepped sequential logic instruction program for controlling therolling mill operation, and in addition receives input informationregarding the known characteristics of each workpiece strip that isroller, and then monitors the respective stand operational results forthe rolling of each workpiece for improving the stored informationwithin its memory. The following is illustrative of the informationwhich enters into the operation of such a control system: The desireddelivery gauge and temperature from the last stand is supplied to thecomputer as known input data, the entry temperature to the firstfinishing stand is estimated or is deter mined by an entry pyrometer;the entry gauge to each of the finishing stands is known since this isthe delivery gauge from the last preceding finishing stand; the entrywidth to the finishing stands is supplied as input information or can bemeasured by a suitable width gauge.

After the head end of a given workpiece has passed through each of thefinishing stands, such gauge effecting variables relative to theremainder of the workpiece as changes in workpiece temperature, hardnessvariations caused by hard spots, roll wear and the like are controlledby the conventional roll force gauge control system operative withindividual stand roll force sensing load cells as well known to personsskilled in this particular art. These load cells measure and provide thestand actual roll force signals to the screwdown or rollopeningregulators which are operative with a reference roll force to determinethe adjustments made to the respective stand roll openings as requiredto deliver a desired workpiece gauge out of each stand of the rollingmill.

In general, a programmed digital process control computer can include acentral integrated process control or setup processor, with associatedinput and output equipment, such as generally described in an articleentitled Understanding Digital Computer Process Control," by B. H.Murphy, which appeared in Automation Magazine for Jan. 1965, pages 71 to76.

A background description of process control computer application for adynamic operation such as the control of a hot strip tandem rolling millcan be found in an article entitled Programming For Process Control byPaul E. Lego in the Jan. 1965 Westinghouse Engineer at pages 13 to 19,and in another article entitled Computer Program Organization For AnAutomatically Controlled Rolling Mill" by John S. Deliyannides andArthur H. Green in the 1966 Iron and Steel Engineer Year Book at pages328 to 334. An additional article of descriptive interest here isentitled On-line Computer Controls Giant Rolling Mill" by Alonzo F.Kenyon appeared in the Nov. 1965 Westinghouse Engineer at pages 182 to187.

It is known and understood by persons skilled in this particular art ofapplying process computer control systems that a combined hardware andsoftware process control system, or an extended special purpose controlcomputer apparatus which is produced when a general purpose digitalcomputer is operated under the control of a predetennined softwareinstruction program, such as illustrated by the functional program flowchart shown in the attached drawings, can also be built using hardwareor wired logic programming in view of the recognized general equivalenceof a software pro gramming embodiment and a hardware programmingembodiment of substantially the same control system. However, when aninvolved industrial application such as here-described becomes somewhatcomplex, the economics tend to favor the software approach due to theotherwise greater expense and lack of flexibility when logic circuits,such as the well-known NOR logic circuits, are wired together to providethe desired hardware programming circuit arrangement buildup of suchlogic circuits to perform the sequential program steps.

The use of a conventional roll force automatic work strip gauge controlsystem for providing a substantially constant workstrip gauge orthickness for the remainder length of the workstrip out of one or morestands of the rolling mill after the head end of the workstrip hasthreaded all the stands is well known to a person skilled in thisparticular art. For example, a published article of interest to give abackground understanding of the involved concept, can be found in the1964 Iron and Steel Engineer Yearbook at pages 753 to 762 by John W.Wallace and is entitled Fundamentals of Strip Mill Automatic GaugeControl Systems." Another article of interest appeared in the Mar. 1964Westinghouse Engineer at pages 34 to 40 by J. W. Wallace and wasentitled Strip Mill Automatic Gauge Control Systems.

The use of an on-line digital computer control system requires that oneor more model equations relating to the controlled process be stored inthe memory unit of the computer to enable predictive operation andcontrol of the process and adaptive control of the process relative toupdating information obtained from actual operation of the process. Forthe example of a rolling mill, to permit a prediction of each stand rollforce, relative to a given workpiece having a known grade, a suitablemodel equation is used to predict the roll force for each stand, and inrelation to the desired reduction to be made in each stand the unloadedroll opening is predicted for each stand. This general information isalready known by persons skilled in this art and is covered by severalpublications; for example, in the Iron and Steel Engineering Yearbookfor 1962 at pages 587 to 592 is an article dealing with this subjectmatter, and two more articles can be found in the Iron and SteelEngineering Yearbook for 1965 at pages 461 to 467 and pages 468 to 475.A further publication of interest here to illustrate the rolling millcomputer control environment in which the teachings of the presentinvention could be utilized can be found in the Westinghouse Engineerfor Jan. 1969, pages 2 through 8 by John W. Wallace and is entitledIntegrated Process Control Rolls Steel More Efficiently.

CROSS REFERENCE TO RELATED APPLICATIONS The present invention is relatedto the inventions disclosed in copending patent applications Ser. No.728,469 filed May 13, 1968 and Ser. No. 787,173, filed Dec. 26, 1968 andassigned to the same assignee as the present application.

SUMMARY OF THE INVENTION In accordance with the general principles ofthe present invention at least one rolling mill stand is under thecontrol of a process control computer for providing a desired deliveryworkpiece strip gauge or thickness from that stand in relation to storedand weighted information learned from and classified according to theprevious rolling of prior similar batches or groups of workpieces. Astand operation control system is provided which takes advantage ofstored rolling experience information gained from the previous rollingof prior batches of similar workpieces. Measurements are made during therolling of each workpiece group to determine whether the generaloperation level should be higher or lower relative to model equationpredicted stand operation values, and from this determination and forsubsequent groups of similar workpieces, corrections are determined andstored to compensate when needed for each rolling mill stand operation.The target thickness to be delivered from each stand for subsequentworkpiece groups is maintained in this manner better than can bedetermined from the original schedule calculation using provided modelequations.

It is therefore a general object of the present invention to provide anew and improved gauge control system for establishing weightedoperation correction information re garding previous rolling of similargroups of workpieces which is stored in classified locations to improvethe rolling of subsequent similar groups of workpieces.

A further object of the present invention is to provide a new andimproved workpiece gauge or thickness control system for the operationalcontrol of at least one mill stand, wherein a prediction of selectedsetup values is made based upon operational model equations for theknown workpiece being rolled and this prediction is then corrected inrelation to weighted information stored in a predetermined mannerrelative to the previous rolling experience with at least one similarworkpiece in that same mill stand.

An additional object of the present invention is to provide a new andimproved gauge control system for a known workpiece passing through atleast one mill stand, wherein operation correction ratios areestablished between actual stand operating variables in relation topredicted values for said variables, which correction ratios arecompared to weighted and previously learned corrections for those sameparameters as obtained from previous rolling experience with at leastone similar workpiece.

A still further object of the present invention is to provide a new andimproved workpiece gauge control system whereby subsequent rolling by agiven stand of a known workpiece is responsive to learned informationobtained and arranged in a predetermined manner from previous rollingexperience with prior similar workpieces to better control the rollingof that known workpiece.

An additional object of the present invention is to provide an improvedworkpiece delivery gauge or thickness control for a rolling mill,including one or more stands, wherein relative to at least onepredetermined predicted mill operation variable for the previous rollingof a similar classification of workpiece, the same variable was measuredduring actual operation of the rolling mill when the previous workpiecewas being rolled and was compared with the predicted value of this samevariable to provide a stand operation correction factor; this correctionfactor was weighted and then stored away in a selected memory locationclassified by workpiece definition such that the correction factor isavailable to improve the sub sequent rolling of the same classificationworkpiece at a later time; in this way, predicted stand operationdetermining variables, such as roll force and unloaded roll gap settingsare continually improved and better tuned relative to the utilizedrolling operation model equations.

A different object of the invention is to provide an improved workpiecedelivery gauge control for particularly the head end of a workpiecepassing through a rolling mill which has at least one stand and whereinat least roll force stand operation correction factors are determinedfor the predicted operation of each of the stands as compared to theactual operation of said stands, and wherein these correction factorsare stored away in accordance with a predetermined classification of theworkpiece spectrum desired to be rolled by the mill, for improving modelequation predicted operation of each rolling mill stand relative tosimilar workpieces to be rolled at some future time subsequent to theprevious determination of said stand operation correction factors for atleast one previous similar workpiece rolling experience.

The above and other objects and features of the invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings, which form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic showing of aworkpiece rolling mill, including the last stand of the roughing mill,the crop shear, and a generalized showing of the finishing mill suitablefor operation with the control of the present invention;

FIG. 2 is a showing of the initial storage of stand operation correctionfactors for a typical stand N to illustrate the classification relativeto workpiece gauge and grade;

FIG. 3 shows the storage of operation correction factors for a typicalstand N after some actual rolling experience has provided weightedvalues for many of the workpiece category classified correction factors;

FIG. 4 shows the logic flow chart for the instruction program operativebefore each workpiece enters the respective rolling mill stands to indexthe grade and gauge of this next workpiece and to provide an operationcorrection factor for each stand to adapt the model equation predictedoperation variables such as stand roll force.

FIG. 5 shows the logic flow chart for the instruction program operativeafter a workpiece has entered each of the stands to determine theimproved stand operation correction factors for the next succeedingsimilar workpiece;

FIG. 6 shows the logic flow chart for the instruction program operativeafter a workpiece has entered each of the stands, which workpieceinvolves a change of either gauge or grade relative to the previouslyrolled workpiece to transfer the previous workpiece stand operationcorrection factors as desired into the computer memory.

FIG. 7 illustrates in general the operating range of the model equationsfor the control of a typical stand relative to the desired operatingspectrum of workpieces to be rolled by that stand to show the realizedadaptation in accordance with the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT With reference to FIG. 1, aportion of a continuous strip rolling mill is shown and designatedgenerally by the reference numeral 10. The last stand R of the roughingmill is followed by the first two stands F1 and F2 and the last stand FNof a finishing mill. Each of the rolling stands includes a pair of workrolls l2 and 14, which are given a model equation predicted unloadedscrewdown setting SD to provide a desired strip reduction as a workpiece16 passes successively through each of the several stands. A set ofbackup rolls l8 and for each stand provides pressure or force on thework rolls 12 and 14 in response to the operation of a screwdownmechanism 22. The stand roll force is applied through operation of ascrewdown motor 24 controlled by a screwdown position regulator 26.Respective stand screwdown position detectors 28 monitor the positionsetting of the screwdown 22 for each stand by detecting the screwdownposition change as indicated by the revolutions of the screwdown motor24 and transmitting an output signal representative of the screwdownposition setting. Following the last finishing stand FN, an X- ray gauge30 detects the actual delivery gauge of the workpiece and provides asignal proportional thereto. The product of this X-ray determineddelivery gauge of the workpiece and the exit speed of the workpieceleaving the last stand FN can be compared with the like product for eachof the other stands for determining the mass flow delivery gauge fromthose other stands. This is compared with the roll force gauge todetermine the stand ofiset correction. Associated with each of therespective rolling stands is a roll force sensing load cell 32 whichmeasures the separating roll force FM at its associated respective standfor this purpose.

Between the last roughing stand R and the first finishing stand F1 is acrop shear 23, and a temperature measuring device such as the pyrometerto measure the actual temperature of the head end of the workpiece at apredetermined location near the crop shear 23 where the workpiece is onits way into the first finishing stand Fl. It should be understood thatthe stand position showing of FIG. 1 is illustrative and in normalpractice, the tail end of a given workpiece strip will leave the lastroughing stand R before its head end enters the first finishing standFl.

Control of the rolling process is determined by a programmed digitalprocess control computer 34 which provides desired correlation betweenthe various rolling mill input and output information in a predeterminedmanner. The exact mode of control is provided by at least oneinstruction program operative with the computer to functionally relatethe respective input signals or combination of input signals to providesuitable output control signals, which are operative to provide thedesired delivery of on-gauge workpiece strip from each stand and thedesired operation of the rolling mill. The functional relationshipbetween the respective inputs within the process computer 34 will be setforth in detail hereinafter. Other well-known component apparatus andstructure contributing to the proper operation of the rolling mill, andancillary to the disclosure of the present invention, have beenpurposely left out of this description for ease of illustration, andwould include such items as drive motors, sensing potentiometers, speedcontrollers and the like.

Accurate online gauge control and regulation of particularly theworkpiece head end is achieved by a plurality of model equationrelationships operative with the process control computer to providepredicted operation determining setting reference values for each stand,such as a predicted roll force for each stand and from this acorresponding screwdown setting reference signal from the processcontrol computer 34 to the respective stand screwdown positionregulators 26 corresponding to each of the rougher stands and thefinishing stands. This is initially done in relation to predeterminedand empirically determined model equation information for the knowncharacteristics of the workpiece strip.

As the initial operation of the present control, and before a givenworkpiece strip enters the finishing mill stands, the computer 34predicts the roll forces for the respective stands of the finishing millusing actual delivery height from the last roughing stand in relation toknown roll force and horsepower model equations and known workpiececharacteristics, the desired horsepower loading of the respectivestands, and in relation to the mill spring for each of those stands andthe desired or target delivery gauge out of the last stand of thefinishing mill. The screwdown setting for each stand is determined inrelation to the calculated or predicted stand roll separating force, andthe position regulator for each stand makes the required screwdownadjustment.

There is stored in the computer memory a model equation to calculate theaverage roll pressure for each stand as required to make the desiredreduction in the workpiece strip to be made by that stand; this equationis a follows:

The stand average roll pressure is the analog determined by thisequation, where T,, is the nominal workpiece strip tem perature indegrees Fahrenheit for the given stand 11, P is the average pressureacross the arc of contact or the resistance to deformation in p.s.i., Hnis the desired delivery gauge out of stand n, Dn is the work rolldiameter of stand n, and H(n-1 is the input workpiece strip gauge intostand n. The constants Al through A5 are parameters relating toworkpiece grade and are arrived at empirically for the particularworkpiece strip alloy or grade involved; these are obtained empiricallyby rolling many workpiece strips of a known alloy and measuring thestand roll forces for known drafts and known workpiece striptemperature, then by mathematical regression the actual constants aredetermined by least squares fitting relative to any resulting error. Thepredicted roll force for each stand is then calculated by the modelequation: Fn=[P-.67TPSI(n1).33TPSI(n)] The term TPSl(n-l) is the entrytension to the stand n, the term TPSI(n) is the delivery tension fromthe stand in, and W is the width of the workpiece strip. A third modelequation is used to calculate the desired reduction to be made at standn in relation to the desired horsepower loading for stand n, as follows:

[TPSI(n)TPSI(n-I)]W (IPSLS) (HLS) 0.151 The term [P812 is the speed ofthe particular stand n, the term IPSLS is the speed of the last standand the term HLS is the desired delivery gauge of the workpiece stripfrom the last stand. it should be noted that each of these equations arein relation to the draft or thickness reduction to be made in theworkpiece strip by each particular stand n.

The roll force predictions are developed through the above mathematicalmodel equations stored in the memory of the process control computer 34,and then modified for providing a desired control of the rolling mill inresponse to the various signals resulting from several operatingcondition sensing devices such as the respective load cells 32, thestand speed sensing devices 15, the screwdown position detector 28 andso forth.

Once all stands of the mill are full, such that the head end of theworkpiece has passed through the last finishing stand FN, the processcontrol computer 34 is then operative in conjunction with a well-knownand conventional roll force gauge control system to maintain for theremainder of the workpiece a desired delivery gauge from each stand withthe benefit of the rolling operation already being substantially ongauge due to the operation of the here described present controlarrangement.

In FIG. 2 there is illustrated for a typical stand N the initiallystored operation correction or adaption factors such as provided inmemory before any classified gauge and grade category workpiece haspassed through the stand for which FIG. 2 applies.

In FIG. 3 there is illustrated for the typical stand N the storedoperation correction factors to show the modifications that occur forworkpiece delivery gauge and grade combinations that have had somerolling experience with this stand. Where the correction factors havenot changed relative to FIG. 2, this could indicate that the modelequation was proper for the rolling by this stand of the particulargauge and grade combination workpiece or that no such workpieces havepassed through this stand. The full desired spectrum of classifiedworkpiece gauge and grade combinations is shown, and it may in actualpractice with a rolling mill be a considerable period of time before agiven workpiece combination passes through the mill stand, if it everdoes, during the normal commercial rolling practice followed by arolling mill.

The present control system operates to take the inertia out of theworkpiece rolling process, so the workpiece can change, for example asubstantial change in grade or the height can change for succeedingworkpieces from 50 mils to 250 mils, and not have an undesired delaybefore the rolling mill operational process can adapt to this newworkpiece. The prior art control systems, where the model equationvariables had not been adequately manipulated through data regressiontechniques required the rolling of workpieces once a workpiece changeoccurred to be able to deliver a more-or-less acceptable height productout of the last stand of the mill.

The control system disclosed in the above-referenced copending patentapplication Ser. No. 787,l 73 was responsive to the grade and gauge ofeach succeeding workpiece relative to the present batch of similar gradeand gauge workpieces being rolled to see if a change had occurred; ifthere was a workpiece change in this respect, the control operation wentback to a one or initialized value for each stand operation correctionfactor. Upon a change of workpiece relative to gauge or grade, all theaveraged and learned stand operation correction factors for previousworkpiece rolling were not saved and returned to a one value again. Itshould be noted that a workpiece width change or a workpiece per unitdraft change was not sensed by this prior control system and can be veryimportant to determined the rolling operation.

The commercial significance of the present invention is that it permits,in a very short time cycle, a given rolling mill to more rapidly rollcommercially acceptable work product over a total desired spectrum ofwork product, in reference to at least one workpiece variable such asgauge or grade, and if desired additional variables such as width andper unit draft. An empirical model equation can be provided to predictapproximately the mill stand operation, but it deviates from the actualphysical rolling mill operational process; by curve fitting andregression techniques, it can be made to better fit the actual process,but there still remains the need for a better adaptation and correlationof this model with the actual process. By rolling one of each workpiececategory in the total desired commercial spectrum this present controlsystem permits substantially improved rolling of all succeeding similarworkpieces. The initial gross or loose fit of the model equations is inthis way adapted or fitted to the actual process. It is very common fora typical rolling mill to roll under automatic control a rather narrowrange of workpiece category groups for a period of time, such as 6months, and many such mills never roll the total desired commercialspectrum of work products under automatic control because of thedifficulty of fitting the model equations to the actual process throughinability to obtain data and adequate operational experience relative tomany workpiece categories.

In actual practice the model equations are not able to depict the actualrolling process percent, such that the stand operation correction factorhere described for each stand will not always remain a one value. Byregression techniques and so forth, the model equation can be made tomore-or-less approximately fit the actual rolling process. The modelequations used to determine the control of a tandem rolling mill haveseveral parameters, which are adjustable through regression after datacollection from monitoring of the actual process. By adjusting theseparameters to better predict the operation of a particular rolling mill,an effort is made to ac ceptably fit the model equations to the actualrolling mill process. By such modification of the model equations aneffort is made to more closely approach a commercially acceptable fitwith the actual process such that commercially acceptable work productis thereby obtained. This fitting operation can be very time consuming,and in actual practice it never really ends; typically, the controlsystem supplier agrees upon a reasonable operational specification suchthat the control system performs satisfactorily for a limited range ofworkpiece grades such as grades 0, l and 2. Then the customer may try toextend the model equation and control system fit for the rest of thedesired workpiece grades from 0 up to 9.

The control system of the present invention improves upon this priorpractice by retaining as learned information all of the acceptable pastcorrelation between predicted and actual mill stand operation in theform of credibility indicating stand operation correction factors, andthen adapts the model equations in this way in accordance withclassified workpiece groupings such as gauge and gade combinations. Thiscan be extended to classify this information according to the variouswidth groupings such as wide, medium and narrow, and selected categoriesof per unit draft groupings. In this way there is established acorrelation between the actual process in relation to the empiricalmodel equation predictions for each workpiece variable, such as gradeand gauge and per unit draft and width, as previously mentioned.

The temperature variable included in the model equations is utilized ina different manner, as compared to the above variables, to modify theprediction of stand scheduled settings; a comparison is made of themeasured temperatures of succeeding similar workpieces and is used as amultiplying correction to compensate for temperature changes.

in FIG. 7 there is shown an illustration of a typical workpiece productspectrurn required for commercially satisfactory operation of a typicalrolling mill. This is shown to be broader than the reasonably obtainablecommercially satisfactory operating range of the model equations per sethat are available to control such a rolling mill. The stand operationcorrection factors in accordance with the present invention areeffective to extend as shown this range of the model equation operationto include the total desired workpiece product spectrum, for thesituation where a sufiicient group of similar classification workpieceshas been previously rolled. The temperature compensation in relation tothe difference between the present workpiece measured temperature andthe previous similar category of workpiece measured temperature iseffective as shown to extend partially the range of the model equationoperation.

In the prior art rolling practice, the model equation parameters wereadjusted and worked on off line. The process control computer loggeddata for each stand during the actual rolling mill operation, and thenthis data was studied off line for the desired regression fitting. Oneset of model equation parameters was provided for each workpiece grade,and was used for the total height range within that grade. It could take4 or 5 years of substantial effort to even partially fit the modelequation to the desire spectrum of work product since a particular millmay only seldom go outside of three grades of work product such that thewhole spectrum of work product might not be adequately covered for aconsiderable period of time.

In accordance with the present invention, if the model equationpredicted value of a stand operation variable such as roll force iswithin 50 percent of the actual stand operation value, this isacceptable and the control system can adapt to the rolling milloperation. If outside 50 percent, then it is necessary to manipulate themodel equation through data collection and so forth as previouslymentioned. This 50 percent limit is arbitrarily chosen to indicate thereis enough intelligence in the model equation for satisfactorily stableoperation of the rolling mill. This limit operates to ignore bad datamonitored from the operation of the mill and to permit a reasonableresponse to the process.

A weighting operation takes place regarding information gathered withina workpiece group and in addition another weighting operation takesplace regarding information for a plurality of groups. One suchweighting is in regard to the number of workpieces within an individualbatch or group of workpieces and the other is regarding batches ofsimilar workpieces. For a given batch of similar workpieces, anypreviously determined stand operation correction factor SCF relative topreviously rolled batches of similar workpieces is transferred from drummemory to temporary core memory and is used in whole to modify the modelequation predictions of stand settings for the rolling of the firstworkpiece. The weighting within core memory for the second workpiecethen changes to become one-half old SCF and one-half the new SCFdetermined after rolling the first workpiece. The weighting for thethird workpiece then changes to become two-thirds old SCF and one-thirdnew SCF after rolling the second workpiece. The weighting for the fourthworkpiece then changes to become three-fourths old SCF and one-fourthnew SCF after rolling the third workpiece, and so forth up to anarbitrary limit, such as workpieces where the weighting remainsnine-tenths old and one-tenth new information. After rolling all of theworkpieces in a given batch, the resulting SCF is transferred fromtemporary core memory and stored on the drum memory of the computer in afurther weighting relation ship determined by the number of such batchesof similar workpieces that have been rolled, with the latter weightingbeing similar to the core memory weighting above described only relativeto the number of batches of similar workpieces that have been rolled. Inaddition there is associated with the drum memory the total number ofsimilar workpieces as well as the number of batches of similarworkpieces for which a given classification of SCF information has beenstored on the memory drum. A counter is provided to keep track of thenumber of similar workpieces in each given batch, and before this latternumber is destroyed, the drum memory keeps track of the total number ofworkpieces in each classified workpiece category involved in the pastrolling history of each stand of the rolling mill as well as the totalnumber of workpiece batches as an index on the drum memory. For example,if there is information stored on the memory drum for 3,500 groups of atotal of 35,000 similar workpieces, then after a given batch of similarcategory workpieces is completed, the weighted SCF information stored intemporary core would be transferred onto the drum in the weightingrelationship of nine-tenths old SCF information already stored on thedrum and one-tenth new SCF information, since there were more than 10groups or batches of SCF information already stored on the drum memory.It should be understood that the number 10 is an arbitrary limitestablished as adequate for the learning operation to follow typicalmill characteristic changes for some particular rolling mill, perhapsfor a different rolling mill this limit should have a different valuedepending upon the particular mill to be controlled.

Thus for the rolling of a new classified workpiece category for eachstand, such as would result from a gauge or a grade change, the initialSCF information transferred into core storage is whatever is on drum forthe new workpiece category and all of this SCF is utilized to adapt themodel equation for the corresponding rolling stand in regard to thefirst workpiece in this new group. Then for the second workpiece in thatsame group, the SCF determined for each stand after the first workpiecepasses through the mill is combined in temporary core storage asone-half old SCF from drum and one-half new SCF. Then for the thirdworkpiece in same workpiece group, the SCF determined after rolling thesecond workpiece is combined in temporary core as two-thirds old SCFplus onethird new SCF, and so forth. For all of this same workpiececategory group after ten, the core SCF is obtained as ninetenths old SCFand one-tenth new SCF, even if 30 or 40 similar workpieces or more ofthis same workpiece group are rolled.

After this particular group of workpieces is completed, whateverweighted SCF information is now in core storage for each stand is thentransferred onto the drum storage with the second weighting aspreviously set forth.

If desired, the control technique can include a 10x10 correction factormatrix for the total width range; on the other hand, if three widthranges (or even ten such categories of width are involved) then thestorage matrix becomes classified by 10 gauge categories and by 10 gradecategories and by the number of width categories, and so forth, per unitdraft can be used instead of width, or even as 10 categories of per unitdraft in addition to the 10 width categories to make the storage matrixclassified according to 10 gauge by 10 grade by 10 width by 10 per unitdraft categories.

In FIG. 4, there is shown a logic flow chart to illustrate theinstruction program which is entered onto whenever a workpiece advancestoward the rolling mill to pass through the respective stands of therolling mill. The program begins at step 200. At step 202 the knowngauge A for the new workpiece having a category of gauge 1 if thedesired delivery thickness from the last stand of the rolling mill isless than 50 mils, having a gauge category 2 if the desired deliverythickness from the last stand of the rolling mill is greater than 50mils and less than 60 mils, having a gauge classification 3 if thisdelivery thickness is less than 72 mils and greater than 60 mils, havinga gauge classification 4 if this delivery thickness is less than 86 milsand greater than 72 mils, having a gauge classification of 5 is thisdesired delivery thickness is greater than 103 mils and less than 86mils, a gauge classification of 6 if the delivery gauge is less thanmils and greater than 103 mils, a gauge classification of 7 if the laststand delivery gauge is less than mils and greater than 125 mils, agauge classification of 8 if the last stand delivery gauge is less thanmils and greater than 150 mils, a gauge classification of 9 if the laststand delivery gauge is less than 220 mils and greater than 180 mils,and a gauge classification of 10 if the last stand delivery gauge isequal to or greater than 220 mils. At program step 204 there is placedinto storage the grade B index of to 9 categories, which are supplied asinput information relative to the known characteristics of theworkpiece. At program step 206 a determination is made if this nextworkpiece to be rolled is the same gauge index as the last workpiece. Ifit is, the program advances to step 208 where a check is made to see ifthis next workpiece is the same grade as the last workpiece. If eitherof program steps 206 or 208 indicates a N0 response, the programadvances to program step 210 where a transfer from drum memory to corememory is made for the respective stand operation correction factors forthe new workpiece of gauge A and grade B. At program step 212 anidentification is made of the location in temporary core memory of thepreviously calculated operation correction factor for each stand for theprevious workpiece grouping of gauge C and grade D. At program step 214,there is made a transfer within temporary core memory storage of theoperation correction factors for each stand as determined at programstep 212 for the old gauge C and grade D workpieces. The program thenadvances to step 216 where a calculation is made of predicted force forthe respective stands of the rolling mill using available modelequations. At program step 218, a modification of the predicted forcevalues takes place using the respective stand operation correctionfactors for the new gauge A and grade B workpiece. At program step 220,the process control computer determines the schedule calculations andmill set up and sequences the rolling mill to roll the new gauge A andgrade B workpiece.

In the event that the check provided at each of program steps 206 and208 indicated that the next workpiece was the same gauge and the samegrade as the last workpiece, the instruction program advanced directlyto block 216 where the model equation predicted variables werecalculated using the modified stand correction factors for theparticular gauge and grade workpiece about to enter the mill.

In FIG. 4 the instruction program is seen to provide a bookkeepingfunction to sense if the next workpiece is the same as the previouslyrolled workpiece, and if it is, then it is not necessary to access a newstand operation correction factor location in the drum storage matrixfor this next workpiece and is not necessary to transfer the previousworkpiece information to the temporary core memory. If either gradeindex or the thickness index changes, a new block of information istaken out of drum storage for determining the roll of the new categoryof workpiece, and it is necessary to store the old workpiece informationinto temporary core storage locations. The stand correction factorvalues regarding the new workpiece are then utilized to adapt the modelequation predictions for the rolling of the new workpiece.

In FIG. 5 is shown the flow chart for the instruction program whichbecomes operative after a first workpiece has threaded all the standsand the sampling of feedback data is obtained on this workpiece. Atprogram step 250, the instruction program is entered. At program step252, a check is made to see if the number of workpieces NC(A,B) alreadyrolled for the new gauge A and grade B workpiece is greater than 10. IfNC (A, B) is greater than It), then program step 254 provides anarbitrary limit of to the number of workpieces. The program advances tostep 256 where a new SCF information weighting NEW WTG(A, B) relative tothe workpiece number of gauge A and grade B is set equal to one over thenumber of workpieces NC (A, B). The program then advances to step 258,where the weighting OLD WTG (A, B) for the old SCF information is setequal to the quantity one minus the new SCF information weighting NEWW'I G (A, B). At program step 260, the program begins with the firststand of the rolling mill by setting stand N equal to one. The programthen advances to setup 262 where a check is made to see if stand N is inoperation. If it is, the repredicted roll force FRP for stand N iscalculated as the square root of the quantity I-IM(N1 which is the rollforce measured delivery gauge from the previous stand minus HM( N) whichis the roll force measured gauge from stand N, divided by the quantityH(N1) which is the predicted delivery gauge from the previous standminus H(N) which is the predicted delivery gauge from stand N, times thequantity FP(N) which is the model equation predicted force for stand N.When N is the first finishing stand, HM(N1 is the last roughing standdelivery gauge. The instruction program then advances to step 266 wherea tentative correction factor TCF(N) is determined for each stand as themeasured force for stand N divided by the repredicted force for stand N.At instruction program step 268, a check is made to see if the tentativecorrection factor TCF (N is greater than 50 percent, and if it is not,the tentative correction factor calculation is considered to be invalidand the program advances to step 270 where N is set as the nextsucceeding stand and the calculation loops back to step 262. On theother hand, if the check made at step 268 is satisfied, the programadvances to step 272 where a check is made to see if the tentativecorrection factor TCF(N) is less than percent. Again, if this check isnot satisfied, the program advances to step 270 as previously described.Steps 268 and 272 provide a validity check on the assumption that if thetentative correction factor is greater or less than an indication of a50 percent error in the measured force compared to the repredictedforce, it is assumed that the information is not acceptable for thepurpose of this example. If the checks made at step 268 and 272 aresatisfied, the program advances to step 274, where a new stand operationcorrection factor relative to the new gauge A and grade B workpiece isdetermined, as the tentative correction factor for stand N times the newinformation weighting factor as determined at program step 256 for thegauge A and grade B workpiece, plus the old stand correction factor forthe gauge A and grade B workpiece (as taken out of the drum memory anddetermined by previous rolling history of this particular stand relativeto the previous groups of the gauge A and grade B workpieces) times theoid information weighting factor for this category of workpiece asdetermined at instruction step 258. The instruction program thenadvances to the step 270 where the program repeats for successivestands, until N becomes the stand after the last stand which is aninoperative stand, such that a tentative correction factor and a newstand correction factor is determined for each of the operating standsin the rolling mill. Program step 262 provides a check for standoperation; and for an operating stand the program advances to step 264;for a nonoperating stand the program advances to step 276, where themeasured height for the present stand is set equal to the height out ofthe last previous stand and the program advances to step 278. At programstep 278 a check is made to see if stand N is the last stand of therolling mill; if it is not, the program advances to step 280 where N isadvanced by one and the program returns to step 262. On the other handif the check made in step 278 indicates that N is the last stand of therolling mill, the program advances to step 282 where a check is made tosee if gauge A index of the new workpiece is the same as the gauge indexof the previous workpiece. If it is, the program advances to step 284where a check is made to see if grade B of the new workpiece is the samegrade as the previous workpiece. If it is, the program advances to step286 which is the end of the logic flow chart. On the other hand,ifeither of steps 282 or 284 indicate a change of gauge or change ofgrade respectively, the program advances to step 288, where a bid ismade for the SCF update program set forth in FIG. 6.

In summary, the FIG. 5 instruction program calculated the informationweighting for old SCF information and new SCF information. A check ismade to see if each stand is operating, and if not that particular standis ignored; while for each stand that is operating the stand force isrepredicted on the basis of measured gauge. A tentative correctionfactor for each stand is calculated and limit checked and then the standcorrection factors are calculated. The required determination is made tosee if a given workpiece is the first workpiece of a new category group,and if it is, a bid is made to do the update operation of the FIG. 6instruction program.

The update operation instruction program of FIG. 6 is entered at step300. At step 302, a transfer is made from drum storage of the standcorrection factor for stand N relative to old workpiece gauge C andgrade D work product for each stand. At step 304, a transfer from drumis made for the weighting WTG (C, D) for the old gauge C and grade Dworkpiece weighting which is common for all stands. At program step 306,a new weighting NEW WTG (C, D) for each stand relative to the oldworkpiece gauge C and grade D work product is set equal to one dividedby the weighting WTG (C, D) previously stored in drum memory. At step308, the old information weighting OLD WTG (C, D) relative to gauge Cand grade D workpiece is set equal to one minus the new informationweighting NEW WTG (C, D) established at step 306. At program step 310the calculation is started with the last stand of the rolling mill bysetting stand N as equal to the last stand. At step 312, the standoperation correction factor SCF (C, D) for stand N relative to gauge Cand grade D workpiece is determined as equal to the new informationweighting NEW WTG (C, D) determined at instruction step 306 times theSCF (C, D) stored in temporary core plus the old information weightingOLD WTG (C, D) determined at step 308 times the stand correction factorSCF (C, D) for stand N obtained from the drum memory as part of programstep 302. The program advances to step 314 where a check is made to seeif N is the first stand, indicating that the stand operating correctionfactors for all stands have been calculated. If it is, then theinstruction program advances to step 316 where the new-calculated standcorrection factor SCF (C, D) for stand N is stored on the drum memoryfor the gauge C and the grade D workpiece, and the program advances tostep 318, where a check is made to see if more than 9 batches ofworkpieces of information are involved in the weighting WTG (C, D). Ifthe answer is yes, the program advances to step 320 where the weightingWTG (C, D) is limited to 10 batches of workpieces. On the other hand, ifthe check made at step 318 is negative, the program advances to step 322where the weighting WTG (C, D) is set equal to the previous weightingplus one. The program advances to step 324 where the weighting WTG (C,D) is stored on drum memory for gauge C and grade D work product, andthe program advances to step 326 where the previous workpiece gauge Cand grade D information core storage location is overwritten with thegauge A and grade B information. The total number of similar pieces ofgauge C and grade D in the last batch of workpieces is added to thetotal previously accumulated number of similar workpieces in programstep 328. The program ends at step 330. In reference to program step 314if the check to see if stand N is not one is negative, the programadvances to step 315 where N is set equal to N-l and the programadvances back through program step 312, where a calculation of the standoperating correction factor is made for the new stand N.

In summary, the update function program of FIG. 6 is operative when achange of workpiece category is identified. It takes the last previousworkpiece batch SCF and adds in a weighted manner to the already storedon drum SCF for similar workpieces.

In general, an operational advantage of the present control arrangementis to store away the accumulatively learned stand N correction factorSCF (A, B) information in a classified manner for the improvement of andbetter model equation adaptation for the future rolling of similar gaugeand grade work product. Relative to the rolling of either one of a newgauge and grade category of work product, any stand correction factorpreviously determined and now stored away for this new gauge and gradework product will be utilized to better control the rolling of this newwork product.

Before any previous history rolling information has been built up andput away in storage locations, all the SCF information values areinitialized to a one value in each storage location for each standrelative to each gauge and each grade combination category. Thisinitially assumes that the model equation should provide the bestavailable stand settings for the rolling mill. For the first rollingexperience relative to a given gauge and grade work product, thisinitialization schedule calculation provides predictions for the rollingconditions and then permits actual rolling of the work product to takeplace using the resulting predicted operation variable, such as rollforce, for each stand. After a given product of known gauge and gradehas been rolled, the measured variable value is compared with thepredicted variable value to determine how well the model equationpredicted values accomplish the desired workpiece reductions anddelivery thickness from such stand or from each pass. Whenever there isa discrepancy, high or low, a stand operation correction factor relativeto the ratio of the measured value to the predicted value of theoperating variable, such as stand roll force, is stored so that wheneverthis same gauge and grade category of work product is again to berolled, this information is available and used, for example, 6 monthslater, when the same product is rolled. This results in an improvementthrough a weighted tuning of the rolling operations. The model equationsestablish the relationships for each stand relative to desired operatingvariables such as roll force, for desired product thickness reductionsand required horsepower on a stand by standard basis. However, the modelequations are predicted upon ideal conditions for the rolling operation,and the actual conditions realized in practice can vary somewhat fromthese ideal conditrons.

It should be understood that stand roll force is readily apparent as asuitable variable to be improved through the stand operan'on learningtechnique in accordance with the teachings of the present invention.However, the schedule calculation requires the prediction of otheroperating variables, such as torques and horsepowers and so forth. Theteachings of the present invention are suitable relative to anyoperational variable that is first predicted and can be subsequentlymeasured, such that a comparison can be made between the actual realizedvalue relative to the predicted value. The improvement or operationcorrection information learned in this manner is classified in apredetermined manner in a storage location within the computer memory.

The control system identifies the gauge and grade category of eachincoming workpiece relative to the operation of each stand from suppliedinput information, such as from punchcards or magnetic tape relative tothe passage of each workpiece through the stand or stands of the rollingmill. After rolling several similar workpieces, the stored old SCF valueis very effective to converge the stand operation to be productive ofdesired delivery work product out of each stand. One of the importantcapabilities of the technique of the present invention is to accuratelycompensate for inherent stand operational characteristics such asapparatus aging and other things which influence the rolling milloperation. The present stand control technique will adequately followand correct for these inherent changes in each mill stand operation.

In accordance with the present invention when the work product changesfrom one grade to another, the following things happened: (I) there isput away in a selected and classified location on the storage drum ofthe process control computer what was learned about the gauge and gradeworkpiece category so that later on today or next week or whenever thissame product is again rolled, there is available an accumulatingimprovement of stored model equation correction data. This involves thenecessary bookkeeping that determines and retains improvementinformation about what was learned during a given work product pass orgroup of passes. (2) Already stored information is taken from drummemory for each stand for the same particular category of work product.(3) There is established the number of workpiece passes or number ofcorrection information pieces in that item that has been previouslyweighted. (4) Another weighting takes place before the now establishedstand correction factor for a given work product is again stored in theselected location on the magnetic drum. It is important that properclassification of the stored SCF information takes place so that it isput away where it can be readily located when the same work product isagain rolled, having the same finished gauge index and grade relative toa given stand. The present invention is particularly important where theavailable model equations under certain conditions are not effective toprovide the correct predictions, and the resulting errors relative to aprevious rolling of a batch of workpieces are corrective adjustment offuture predictions by the same model equations relative to a subsequentrolling of a batch of similar workpieces.

For the convenience of a human operator to understand how well aparticular stand or stands of the rolling mill is operating, the controlcomputer can readily be programmed to provide a printed tablearrangement such as shown in FIG. 3 of individual stand operationcorrection factors which can be displayed to show where the individualstand operations are requiring correction. This can alert an operator toexamine a selected stand of the rolling mill to see why significant oreven undesired stand operation correction factors are occurring relativeto particular stands identified in this manner. Whenever a change occursin the pattern of the resulting stored correction factors, this is oneindication that something about the rolling mill or a particular standor stands of the rolling mill has changed.

In accordance with the present invention, the rolling mill controloperation involves learning from past rolling experience with similarworkpieces and weighting the stand operation corrective influence ofavailable new data relative to already learned and now stored data. Ingeneral, after or some other desired number of similar workpieces havebeen rolled, the individual stand correction factors for a given workproduct should be pretty well converged onto a substantially correctvalue; from then on, for successive passes of similar workpieces in agiven batch, the weighting of new information relative to old isarbitrarily chosen for establishing and maintaining the desiredcredibility of the model equation stand control variable predictions.

Many operating conditions change during the performance of ametal-rolling mill that are very difiicult to identify in advance, sothere is here provided along term follow technique of whatever happensto the rolling mill. The present invention provides a practicaladaptation technique to adjust the available model equations by learningfrom any actual rolling experience with batches of similar workpiecesthat does occur, and classifying this learned information such that itcan be later recalled when desired for the rolling of other similarworkpieces. The resulting operation of the mill is such that startup ofrolling relative to a changed different work product occurs in afraction of the previously required time. The rolling mill operationimproves and better tunes itself by this learning procedure. Thetechnique of the present invention enables a more rapid startup ingetting online of the given rolling mill relative to any particular workproduct previously rolled to produce a more commercially acceptableproduct. The learning technique in this way takes much inertia out ofthe system and more rapidly converges onto very accurate and verydesirable rolling practices.

it should be understood that references herein to temporary core storageand to drum storage are for purposes of illustration. If desired boththe temporary storage and the long tenn storage can be providedelsewhere as may be desired.

It should be further understood that it is within the scope of thepresent invention relative to the operation of some rolling mills, suchas a reversing mill or other single stand mill, for the classificationof the previously learned operation correction information to be inrelation to some other variable than a per stand variable as one of thevariables for the learning table matrix. For example, the learning tablematrix shown in H0. 3 is classified by workpiece gauge and workpiecegrade on a per stand basis. It may instead be desirable to classify thelearned information by workpiece gauge and workpiece grade in accordancewith a per unit draft variable or some other mill operation variablesuch as width or the like.

Although the present invention has been shown in connection with aspecific embodiment, it should be readily apparent to those skilled inthis art that various changes in form and in the arrangement ofoperational steps may be made to suit particular mill requirementswithout departing from the spirit and scope of the present invention.

For example, one particular embodiment of the present invention forcontrolling a rolling mill has been described above; however, anotherrelated embodiment would be suitable for the control of some otheroperating process or device, where a predetermined understanding of theprocess or device such as one or more operation model equations areestablished to enable a prediction or attempt to provide a desiredfunctioning of that proces or device which could be related to amonitored actual functioning of the process or device for the purpose ofenabling an online weighted learning of information regarding anaccumulated history of that actual functioning for the purpose ofadaptive improvement thereof.

We claim as our invention: 1. The method of controlling the thickness ofa present workpiece passed through at least one stand of a rolling mill,after at least one similar workpiece has been previously passed throughsaid stand and after at least one different workpiece has been passedthrough said stand subsequent to said one similar workpiece and beforesaid present workpiece, including the steps of establishing a predictedvalue for a selected operation determining variable for said stand forthe rolling of said present workpiece in accordance with a predeterminedstand-operating relationship for said stand and in ac cordance withknown information about said workpiece,

establishing a modified predicted value of said variable in accordancewith previously learned information relating to the actual value of saidvariable during the previous passage of at least said one similarworkpiece through said stand and which previously learned informationwas retained during the passage of at least said one different workpiecethrough said stand,

and passing the present workpiece through said stand with the operationof said stand being determined by said modified predicted value of saidvariable.

2. The method of controlling the operation of each operating stand of arolling mill relative to present workpiece passed through each saidstand, after one similar workpiece has been previously passed througheach said stand and after one different workpiece has been passedthrough each said stand subsequent to said one similar workpiece andbefore said present workpiece, including the steps of establishing apredicted value for a selected determinative variable of each said standoperation for the rolling of said present workpiece in accordance with apredetermined stand operation model equation for each said stand and inaccordance with known information about said workpiece,

establishing a modified predicted value of said variable for each saidstand in accordance with previously learned information relating to theprevious passage of said one similar workpiece through each said standand which previously learned information was retained during the passageof said one different workpiece through each said stand,

and passing the present workpiece through each said stand with theoperation of each said stand being in accordance with the respectivemodified predicted value of said varia ble for each said stand.

3. The method of claim 1, with said similar workpiece having at leastone of the same gauge index, the same grade, the same width or the sameper unit draft index as does the present workpiece.

4. The method of claim 2, with said similar workpiece having at leastone predetermined workpiece classification in common with the presentworkpiece.

5. The method of claim 1, with said operation determining variable beingstand roll force.

6. The method of claim 2, with said selected detenninative variablebeing stand roll force.

The method of claim 1, with said predetermined stand operatingrelationship being an empirically established model equation.

8. The method of claim 2, with said predetermined stand operation modelequation being empirically established through previous monitoring ofthe actual operation of each said rolling mill stand relative to aplurality of workpieces having different predetermined classificationcategories.

9. The method of controlling the thickness of a second workpiece to bepassed through at least one stand of a rolling mill after a firstworkpiece similar to the first workpiece has already passed through saidone stand, including the steps of accumulating information regarding theactual value of a selected operation determining variable during theactual rolling of said first workpiece by at least said one stand,

establishing an operation correction factor for at least one said standin accordance with a predetermined relationship between said actualvalue of said operation determining variable during the rolling of saidfirst workpiece and a predicted value of said variable established priorto the passage of the first workpiece through said one stand,

establishing if a change in a predetermined workpiece category hasoccurred after the rolling of said first workpiece by said one stand,

establishing a predicted value for said variable for at least said onestand for the rolling of said second workpiece in accordance with apredetermined model equation relative to at least said one stand andwith known characteristic information about said second workpiece,

with said predicted value for said variable being modified by saidoperation correction factor when said change has occurred.

10. The method of controlling the thickness of a second workpiece to bepassed through at least one stand of a rolling mill after at least afirst workpiece similar to the second workpiece has already passedthrough said one stand including the steps of accumulating informationregarding the actual value of a selected operation determining variablefor said one stand during the previous actual rolling of said firstworkpiece by said one stand,

establishing an operation correction factor for said one stand inaccordance with a predetermined relationship between said actual valueof said operation determining variable for said one stand during therolling of said first workpiece and a previously predicted value of saidvariable for said one stand established prior to the passage of thefirst workpiece through said one stand,

establishing if a change in the workpieces rolled by said one standrelative to a predetermined workpiece category has occurred after therolling of said first workpiece by said one stand,

establishing a predicted value for said variable for said one stand forthe rolling of said second workpiece in accordance with a predeterminedmodel operation equation relative to said one stand and in accordancewith the known characteristic information about said second workpiece,

with said predicted value for said variable for said one stand beingmodified by said operation correction factor for said one stand whensaid change in said workpiece category has occurred.

11. The method of controlling the thickness of a first workpiece and asecond workpiece successively passed through at least one stand of arolling mill, including the steps of establishing a predicted operationfor said one stand for the rolling of said first workpiece in accordancewith a predetermined understanding of the operation of at least said onestand and with known characteristic information about said firstworkpiece,

passing said first workpiece through said one stand and ac cumulatinginformation regarding the actual operation of said one stand relative tosaid first workpiece,

establishing an operation correction factor for said one stand inaccordance with a predetermined relationship between said predictedoperation and said actual operation relative to said first workpiece,

establishing if the first workpiece is similar to said second workpiecein relation to at least one selected characteristic of each saidworkpiece,

establishing if another workpiece which is not similar to said firstworkpiece in relation to at least said one selected characteristic haspassed through said one stand after the passage of said first workpieceand before the passage of the second workpiece,

establishing a predicted operation for said one stand for the rolling ofsaid second workpiece in accordance with said predeterminedunderstanding and in accordance with known characteristic informationabout said second workpiece, and

modifying said predicted operation for the rolling of said secondworkpiece in accordance with said operation correction factor when saidanother workpiece has passed through said one stand after the firstworkpiece and before the second workpiece and when said selectedcharacteristic of the second workpiece is substantially the same as saidselected characteristic of the first workpiece. l2. Workpiece thicknesscontrol apparatus operative with at least one stand of a rolling millhaving a pair of rolls for effecting a thickness reduction in each of afirst and a second workpiece, the combination of first means operativewith a predetermined model equation for establishing a predictedoperation of said rolls relative to said first workpiece,

second means responsive to the actual operation of said rolls relativeto said first workpiece,

third means for establishing a predetermined relationship between saidpredicted operation and said actual operation of said rolls relative tosaid first workpiece,

fourth means for determining the similarity between said first workpieceand said second workpiece relative to at least one of the gauge indexand the grade of each said workpiece,

fifth means for determining if another workpiece not similar to saidfirst workpiece relative to at least one of the gauge index and thegrade of the first workpiece has passed between said rolls after thefirst workpiece and before the second workpiece,

said fourth means being operative with said first means for establishinga predicted operation of said rolls relative to said second workpiece inaccordance with said model equation and said predetermined relationshipwhen said second workpiece is determined to be similar to said firstworkpiece and when said another workpiece has passed between said rollsafter the first workpiece and before the second workpiece.

13. In a workpiece thickness control system for a rolling mill having aplurality of roll stands and a mechanism operative with each roll standto control the roll opening through which a present workpiece is passedsubsequent to the passage of an earlier similar workpiece, thecombination of first means operative with at least one model equationfor predicting the operation of each operating roll stand prior to thepassage of said earlier workpiece and relative to known informationabout said earlier workpiece, second means responsive to the actualoperation of each operating stand during the passage of said earlierworkpiece through the roll stands of the rolling mill,

third means for establishing an operation-controlling relationship foreach of said operating roll stands in relation to said predictedoperation and to said actual operation of each such stand relative tothe passage of said earlier workpiece,

fourth means for weighting said operation-controlling relationship inaccordance with the number of workpieces similar to said earlierworkpiece that have passed through the stands of the rolling mill priorto the passage of said earlier workpiece,

fifth means for storing said weighted operation-controlling relationshipfor each of said stands in a memory location classified according to atleast one selected characteristic of said earlier workpiece, sixth meansfor sensing the passage through said roll stands of a workpiecedifferent that said earlier workpiece in relation to at least said oneselected characteristic of said earlier workpiece after the passage ofsaid earlier workpiece and prior to the passage of said presentworkpiece,

with said first means being operative with said model equation and withsaid weighted operation-controlling relationship for predicting theoperation of each operating stand relative to known infonnation aboutsaid second workpiece when said different workpiece has been sensed bysaid sixth means.

14. The control system of claim 13, including seventh means responsiveto said present workpiece being different than said earlier workpiecerelative to at least said one selected characteristic for causing saidfirst means to predict the operation of each operating stand inaccordance with a second weighted operation-controlling relationshippreviously stored away in a classified location corresponding to atleast said one selected characteristic of said present workpiece anddetermined relative to the actual operation of said stand with aworkpiece similar to said present workpiece and passed through saidstand prior to the passage of said earlier workpiece.

15. In a workpiece gauge control system including at least one stand forrolling at least first and second successive workpieces of known desireddelivery gauge index and known grade, the combination of first means fordetermining a predicted operation for at least said one stand forrolling said first workpiece in accordance with at least a predeterminedmodel equation relative to said one stand,

second means for sensing the actual operation of at least said one standin rolling said first workpiece,

third means for determining a stand operation correction in relation tosaid predicted operation and said actual operation for the rolling ofsaid first workpiece,

with said third means establishing a predetermined weighting of saidcorrection in accordance with the number of workpieces of similarpredetermined category as said first workpiece that has already beenrolled by said one stand,

fourth means for sensing when a workpiece difierent than said firstworkpiece in relation to at least said one category has been rolled byat least said one stand after said first workpiece and before saidsecond workpiece,

with said first means determining a predicted operation for at leastsaid one stand for rolling said second workpiece in accordance with saidmodel equation and in accordance with said correction when at least saidone category of said second workpiece is similar to said first workpieceand after said different workpiece has been sensed by said fourth means.

16. In a workpiece thickness control apparatus for a rolling mill havingat least one stand for rolling respective groups of similar workpieces,the combination of first means for storing a first operation correctionfor said one stand for each predetermined category of workpiece rolledby said stand and in accordance with the number of workpieces in a givengroup having a similar workpiece category that has been rolled by saidstand,

second means for storing a second operation correction for said onestand for each said workpiece category to be rolled by said one standand in accordance with the number of groups of a similar workpiececategory that have been rolled by said one stand,

third means for determining a predicted operation for the rolling of afirst workpiece in accordance with a predetermined model equation forsaid one stand and at least one known characteristic of the firstworkpiece,

fourth means for monitoring the actual operation of said one standduring the rolling of said first workpiece,

fifth means for establishing a third operation correction for said onestand in relation to said predicted operation and said actual operationfor the rolling of said first workpiece, with said first means beingoperative to combine said first and third operation corrections into apredetermined weighted correction related to the number of similarworkpieces in the group including said first workpiece that have beenrolled by said stand and then being operative to store the resultantweighted correction. 17. The control apparatus of claim 12, with saidthird means subsequently determining a predicted operation for therolling of a second workpiece similar to the first workpiece.

18. The apparatus of claim 12, with the second means being responsive toa second workpiece to be rolled and having at least said onecharacteristic different than said first workpiece such that said secondmeans combines said resultant weighted correction and said secondoperation correction in a predeter mined weighting related to apredetermined number of similar workpieces that have been rolled by saidstand.

19. The method of controlling at least one stand of a rolling mill,including the steps of storing a stand operation correction factor forat least said one stand in accordance with each of predeterminedclassifications of workpieces already rolled by said stand,

modifying each stored stand operation correction factor corresponding tothe predetermined classification of each additional workpiece that isrolled by said stand through a comparison of a predicted operation forsaid stand with the actual operation of said stand relative to each saidadditional workpiece rolled by said stand, comparing each workpieceabout to be rolled by said stand with a selected previous workpiecealready rolled by said stand to determine if the workpiece about to berolled has a different predetermined classification than did saidselected previous workpiece already rolled by the stand,

and predicting the operation of said stand in relation to each workpieceabout to be rolled in accordance with the stored stand operationcorrection factor corresponding to the classification of the workpieceabout to be rolled. 20. The method of controlling at least one stand ofa rolling mill, including the steps of storing stand operationcorrections for at least said one stand in respective memory locationsclassified in accordance with at least one of the gauge index and thegrade of each workpiece already rolled by said stand,

modifying the stored stand operation corrections corresponding to atleast one of the gauge index and the grade of each additional workpiecerolled by said stand through a comparison of a predicted operation forsaid stand with the actual operation of said stand relative to each saidadditional workpiece rolled by said stand,

comparing each workpiece about to be rolled by said stand with aselected previous workpiece already rolled by said stand to determine ifthe workpiece about to be rolled has at least one of a different gaugeindex and a different grade than did said selected previous workpiecealready rolled by the stand,

and predicting the operation of said stand in relation to each workpieceabout to be rolled in accordance with the stored stand operationcorrection factor corresponding to at least one of the gauge index andthe grade of the workpiece about to be rolled.

21. The method of controlling a product operation and including thesteps of storing operation corrections in respective memory locationsclassified in accordance with at least one predetermined category ofeach monitored product already subjected to said product operation andrelative to a comparison between a predicted operation with each productand a resulting actual operation with that same product comparing eachproduct about to be subjected to said product operation with a selectedprevious product already subjected to said product operation todetermine if the product about to be subjected to said product operationis different regarding at least said one predetermined category,

and predicting said product operation in relation to each product aboutto be subjected to said product operation in accordance with the storedoperation correction corresponding to at least said one predeterminedcategory of the latter product.

22. The method of controlling a predetermined operation relative to aplurality of products and including the steps of establishing apredicted value for a variable determining said operation in accordancewith a predetermined understanding about said operation and inaccordance with

1. The method of controlling the thickness of a present workpiece passedthrough at least one stand of a rolling mill, after at least one similarworkpiece has been previously passed through said stand and after atleast one different workpiece has been passed through said standsubsequent to said one similar workpiece and before said presentworkpiece, including the steps of establishing a predicted value for aselected operation determining variable for said stand for the rollingof said present workpiece in accordance with a predeterminedstandoperating relationship for said stand and in accordance with knowninformation about said workpiece, establishing a modified predictedvalue of sAid variable in accordance with previously learned informationrelating to the actual value of said variable during the previouspassage of at least said one similar workpiece through said stand andwhich previously learned information was retained during the passage ofat least said one different workpiece through said stand, and passingthe present workpiece through said stand with the operation of saidstand being determined by said modified predicted value of saidvariable.
 2. The method of controlling the operation of each operatingstand of a rolling mill relative to present workpiece passed througheach said stand, after one similar workpiece has been previously passedthrough each said stand and after one different workpiece has beenpassed through each said stand subsequent to said one similar workpieceand before said present workpiece, including the steps of establishing apredicted value for a selected determinative variable of each said standoperation for the rolling of said present workpiece in accordance with apredetermined stand operation model equation for each said stand and inaccordance with known information about said workpiece, establishing amodified predicted value of said variable for each said stand inaccordance with previously learned information relating to the previouspassage of said one similar workpiece through each said stand and whichpreviously learned information was retained during the passage of saidone different workpiece through each said stand, and passing the presentworkpiece through each said stand with the operation of each said standbeing in accordance with the respective modified predicted value of saidvariable for each said stand.
 3. The method of claim 1, with saidsimilar workpiece having at least one of the same gauge index, the samegrade, the same width or the same per unit draft index as does thepresent workpiece.
 4. The method of claim 2, with said similar workpiecehaving at least one predetermined workpiece classification in commonwith the present workpiece.
 5. The method of claim 1, with saidoperation determining variable being stand roll force.
 6. The method ofclaim 2, with said selected determinative variable being stand rollforce.
 7. The method of claim 1, with said predetermined stand operatingrelationship being an empirically established model equation.
 8. Themethod of claim 2, with said predetermined stand operation modelequation being empirically established through previous monitoring ofthe actual operation of each said rolling mill stand relative to aplurality of workpieces having different predetermined classificationcategories.
 9. The method of controlling the thickness of a secondworkpiece to be passed through at least one stand of a rolling millafter a first workpiece similar to the first workpiece has alreadypassed through said one stand, including the steps of accumulatinginformation regarding the actual value of a selected operationdetermining variable during the actual rolling of said first workpieceby at least said one stand, establishing an operation correction factorfor at least one said stand in accordance with a predeterminedrelationship between said actual value of said operation determiningvariable during the rolling of said first workpiece and a predictedvalue of said variable established prior to the passage of the firstworkpiece through said one stand, establishing if a change in apredetermined workpiece category has occurred after the rolling of saidfirst workpiece by said one stand, establishing a predicted value forsaid variable for at least said one stand for the rolling of said secondworkpiece in accordance with a predetermined model equation relative toat least said one stand and with known characteristic information aboutsaid second workpiece, with said predicted value for said variable beingmodified by said operation correction factor when said change hasoccurred.
 10. The method of cOntrolling the thickness of a secondworkpiece to be passed through at least one stand of a rolling millafter at least a first workpiece similar to the second workpiece hasalready passed through said one stand, including the steps ofaccumulating information regarding the actual value of a selectedoperation determining variable for said one stand during the previousactual rolling of said first workpiece by said one stand, establishingan operation correction factor for said one stand in accordance with apredetermined relationship between said actual value of said operationdetermining variable for said one stand during the rolling of said firstworkpiece and a previously predicted value of said variable for said onestand established prior to the passage of the first workpiece throughsaid one stand, establishing if a change in the workpieces rolled bysaid one stand relative to a predetermined workpiece category hasoccurred after the rolling of said first workpiece by said one stand,establishing a predicted value for said variable for said one stand forthe rolling of said second workpiece in accordance with a predeterminedmodel operation equation relative to said one stand and in accordancewith the known characteristic information about said second workpiece,with said predicted value for said variable for said one stand beingmodified by said operation correction factor for said one stand whensaid change in said workpiece category has occurred.
 11. The method ofcontrolling the thickness of a first workpiece and a second workpiecesuccessively passed through at least one stand of a rolling mill,including the steps of establishing a predicted operation for said onestand for the rolling of said first workpiece in accordance with apredetermined understanding of the operation of at least said one standand with known characteristic information about said first workpiece,passing said first workpiece through said one stand and accumulatinginformation regarding the actual operation of said one stand relative tosaid first workpiece, establishing an operation correction factor forsaid one stand in accordance with a predetermined relationship betweensaid predicted operation and said actual operation relative to saidfirst workpiece, establishing if the first workpiece is similar to saidsecond workpiece in relation to at least one selected characteristic ofeach said workpiece, establishing if another workpiece which is notsimilar to said first workpiece in relation to at least said oneselected characteristic has passed through said one stand after thepassage of said first workpiece and before the passage of the secondworkpiece, establishing a predicted operation for said one stand for therolling of said second workpiece in accordance with said predeterminedunderstanding and in accordance with known characteristic informationabout said second workpiece, and modifying said predicted operation forthe rolling of said second workpiece in accordance with said operationcorrection factor when said another workpiece has passed through saidone stand after the first workpiece and before the second workpiece andwhen said selected characteristic of the second workpiece issubstantially the same as said selected characteristic of the firstworkpiece.
 12. Workpiece thickness control apparatus operative with atleast one stand of a rolling mill having a pair of rolls for effecting athickness reduction in each of a first and a second workpiece, thecombination of first means operative with a predetermined model equationfor establishing a predicted operation of said rolls relative to saidfirst workpiece, second means responsive to the actual operation of saidrolls relative to said first workpiece, third means for establishing apredetermined relationship between said predicted operation and saidactual operation of said rolls relative to said first workpiece, fourthmeans for deterMining the similarity between said first workpiece andsaid second workpiece relative to at least one of the gauge index andthe grade of each said workpiece, fifth means for determining if anotherworkpiece not similar to said first workpiece relative to at least oneof the gauge index and the grade of the first workpiece has passedbetween said rolls after the first workpiece and before the secondworkpiece, said fourth means being operative with said first means forestablishing a predicted operation of said rolls relative to said secondworkpiece in accordance with said model equation and said predeterminedrelationship when said second workpiece is determined to be similar tosaid first workpiece and when said another workpiece has passed betweensaid rolls after the first workpiece and before the second workpiece.13. In a workpiece thickness control system for a rolling mill having aplurality of roll stands and a mechanism operative with each roll standto control the roll opening through which a present workpiece is passedsubsequent to the passage of an earlier similar workpiece, thecombination of first means operative with at least one model equationfor predicting the operation of each operating roll stand prior to thepassage of said earlier workpiece and relative to known informationabout said earlier workpiece, second means responsive to the actualoperation of each operating stand during the passage of said earlierworkpiece through the roll stands of the rolling mill, third means forestablishing an operation-controlling relationship for each of saidoperating roll stands in relation to said predicted operation and tosaid actual operation of each such stand relative to the passage of saidearlier workpiece, fourth means for weighting said operation-controllingrelationship in accordance with the number of workpieces similar to saidearlier workpiece that have passed through the stands of the rollingmill prior to the passage of said earlier workpiece, fifth means forstoring said weighted operation-controlling relationship for each ofsaid stands in a memory location classified according to at least oneselected characteristic of said earlier workpiece, sixth means forsensing the passage through said roll stands of a workpiece differentthan said earlier workpiece in relation to at least said one selectedcharacteristic of said earlier workpiece after the passage of saidearlier workpiece and prior to the passage of said present workpiece,with said first means being operative with said model equation and withsaid weighted operation-controlling relationship for predicting theoperation of each operating stand relative to known information aboutsaid second workpiece when said different workpiece has been sensed bysaid sixth means.
 14. The control system of claim 13, including seventhmeans responsive to said present workpiece being different than saidearlier workpiece relative to at least said one selected characteristicfor causing said first means to predict the operation of each operatingstand in accordance with a second weighted operation-controllingrelationship previously stored away in a classified locationcorresponding to at least said one selected characteristic of saidpresent workpiece and determined relative to the actual operation ofsaid stand with a workpiece similar to said present workpiece and passedthrough said stand prior to the passage of said earlier workpiece. 15.In a workpiece gauge control system including at least one stand forrolling at least first and second successive workpieces of known desireddelivery gauge index and known grade, the combination of first means fordetermining a predicted operation for at least said one stand forrolling said first workpiece in accordance with at least a predeterminedmodel equation relative to said one stand, second means for sensing theactual operation of at least said one stand in rolling said firstworkpiece, thIrd means for determining a stand operation correction inrelation to said predicted operation and said actual operation for therolling of said first workpiece, with said third means establishing apredetermined weighting of said correction in accordance with the numberof workpieces of similar predetermined category as said first workpiecethat has already been rolled by said one stand, fourth means for sensingwhen a workpiece different than said first workpiece in relation to atleast said one category has been rolled by at least said one stand aftersaid first workpiece and before said second workpiece, with said firstmeans determining a predicted operation for at least said one stand forrolling said second workpiece in accordance with said model equation andin accordance with said correction when at least said one category ofsaid second workpiece is similar to said first workpiece and after saiddifferent workpiece has been sensed by said fourth means.
 16. In aworkpiece thickness control apparatus for a rolling mill having at leastone stand for rolling respective groups of similar workpieces, thecombination of first means for storing a first operation correction forsaid one stand for each predetermined category of workpiece rolled bysaid stand and in accordance with the number of workpieces in a givengroup having a similar workpiece category that has been rolled by saidstand, second means for storing a second operation correction for saidone stand for each said workpiece category to be rolled by said onestand and in accordance with the number of groups of a similar workpiececategory that have been rolled by said one stand, third means fordetermining a predicted operation for the rolling of a first workpiecein accordance with a predetermined model equation for said one stand andat least one known characteristic of the first workpiece, fourth meansfor monitoring the actual operation of said one stand during the rollingof said first workpiece, fifth means for establishing a third operationcorrection for said one stand in relation to said predicted operationand said actual operation for the rolling of said first workpiece, withsaid first means being operative to combine said first and thirdoperation corrections into a predetermined weighted correction relatedto the number of similar workpieces in the group including said firstworkpiece that have been rolled by said stand and then being operativeto store the resultant weighted correction.
 17. The control apparatus ofclaim 12, with said third means subsequently determining a predictedoperation for the rolling of a second workpiece similar to the firstworkpiece.
 18. The apparatus of claim 12, with the second means beingresponsive to a second workpiece to be rolled and having at least saidone characteristic different than said first workpiece such that saidsecond means combines said resultant weighted correction and said secondoperation correction in a predetermined weighting related to apredetermined number of similar workpieces that have been rolled by saidstand.
 19. The method of controlling at least one stand of a rollingmill, including the steps of storing a stand operation correction factorfor at least said one stand in accordance with each of predeterminedclassifications of workpieces already rolled by said stand, modifyingeach stored stand operation correction factor corresponding to thepredetermined classification of each additional workpiece that is rolledby said stand through a comparison of a predicted operation for saidstand with the actual operation of said stand relative to each saidadditional workpiece rolled by said stand, comparing each workpieceabout to be rolled by said stand with a selected previous workpiecealready rolled by said stand to determine if the workpiece about to berolled has a different predetermined classification than did saidselected previous workpiece already rolled by the stand, and predictingthe operation of said stand in relation to each workpiece about to berolled in accordance with the stored stand operation correction factorcorresponding to the classification of the workpiece about to be rolled.20. The method of controlling at least one stand of a rolling mill,including the steps of storing stand operation corrections for at leastsaid one stand in respective memory locations classified in accordancewith at least one of the gauge index and the grade of each workpiecealready rolled by said stand, modifying the stored stand operationcorrections corresponding to at least one of the gauge index and thegrade of each additional workpiece rolled by said stand through acomparison of a predicted operation for said stand with the actualoperation of said stand relative to each said additional workpiecerolled by said stand, comparing each workpiece about to be rolled bysaid stand with a selected previous workpiece already rolled by saidstand to determine if the workpiece about to be rolled has at least oneof a different gauge index and a different grade than did said selectedprevious workpiece already rolled by the stand, and predicting theoperation of said stand in relation to each workpiece about to be rolledin accordance with the stored stand operation correction factorcorresponding to at least one of the gauge index and the grade of theworkpiece about to be rolled.
 21. The method of controlling a productoperation and including the steps of storing operation corrections inrespective memory locations classified in accordance with at least onepredetermined category of each monitored product already subjected tosaid product operation and relative to a comparison between a predictedoperation with each product and a resulting actual operation with thatsame product comparing each product about to be subjected to saidproduct operation with a selected previous product already subjected tosaid product operation to determine if the product about to be subjectedto said product operation is different regarding at least said onepredetermined category, and predicting said product operation inrelation to each product about to be subjected to said product operationin accordance with the stored operation correction corresponding to atleast said one predetermined category of the latter product.
 22. Themethod of controlling a predetermined operation relative to a pluralityof products and including the steps of establishing a predicted valuefor a variable determining said operation in accordance with apredetermined understanding about said operation and in accordance withknown information regarding a present product about to be subjected tosaid operation, establishing a modified predicted value of said variablein accordance with previously learned information relating to the actualvalue of said variable when a previous product was subjected to saidoperation and which previously learned information was retained while alater and different product was subjected to said operation, andsubjecting said present product to said operation in accordance withsaid modified predicted value of said variable.